The present invention relates to an image forming apparatus and a process cartridge removably attached to a main body of an electrophotographic image forming apparatus, and particularly to a protective member used in conveyance and storage of a process cartridge.
Heretofore, in an image forming apparatus which adopts electrophotography, a photoconductor that is an image bearing member has been charged by a charger, light irradiation according to image data has been performed on the charged photoconductor thereby to form a latent image, this latent image has been developed by a developing device, and the developed toner image has been transferred onto a recording medium, whereby an image has been formed.
On the other hand, with colorization of an image, a tandem type color image forming apparatus has been also proposed, which has plural process cartridges in which each of the above image forming processes is executed, forms a toner image of each color of cyan, magenta, yellow, and preferably black on each photoconductor, and multi-layer transfers these toner images onto an endless intermediate transfer member in a transfer position of each photoconductor, thereby to form a full color image.
Since such the tandem type color image forming apparatus has each image forming section of each color, it is advantageous for speed-up.
A conventional tandem type color image forming apparatus will be described below.
FIG. 7 is a diagram showing a state in which a conventional process cartridge protective member is to be attached. In conveyance and storage of process cartridge 2 to 5, by the continuous pressure-contact state between the developing roller 2b to 5b and the photoconductor drum 2a to 5a, contact traces (nip line) of the development roller on a pressure-contact part of photoconductor drum 2a to 5a, and stains on the photoconductor drum 2a to 5a due to oil components of the developing roller 2b to 5b moving from its rubber components are caused. The protective member is attached in order to prevent the contact traces and the stains.
FIG. 8 is a diagram showing a state in which the conventional process cartridge protective member has been attached.
In FIG. 7, reference numerals 14a and 14b are protective members which are inserted into the process cartridge 2 to 5 apart from the center in the longitudinal direction to the left and the right by the predetermined distance, thereby to space the photoconductor drum 2a to 5a and the pressure-contact part (nip part) of the development roller 2b to 5b which are formed in the process cartridge 2 to 5. Further, reference numeral 15 is a photoconductor drum protective cover for protecting the photoconductor drum 2a to 5a exposed to an opening part of the process cartridge 2 to 5. The protective members 14a and 14b are attached in two positions which are right and left symmetrical in order to space the photoconductor drum 2a to 5a and the development roller 2b to 5b uniformly in the axial direction.
FIG. 9 is a diagram showing a state in which another conventional process cartridge protective member is to be attached. This process cartridge protective member has a size covering the nearly entire region in the longitudinal direction of the process cartridge 2 to 5. FIG. 10 is a diagram showing a state in which another conventional process cartridge protective member has been attached. Further, other process cartridge protective members have been also disclosed in JP-A-4-140770 and JP-A-2002-6722.
However, in packing and conveying states of the process cartridge, in case that the process cartridge has been stored for a long period, the pressure-contact state between the developing roller and the photoconductor drum is continued, whereby such a problem is produced that the contact traces (nip line) of the development roller are produced on the pressure-contact part of the photoconductor drum, or the photoconductor drum surface is stained with oil components moving from rubber components of the developing roller. In order to solve such the problem, the countermeasure as described in the above background art has been taken. However, in the conventional constitution, since the members for spacing the photoconductor drum and the development roller must be attached in the right and left two positions in the longitudinal direction of the process cartridge, the two operations must be performed in packing or renewing the process cartridge. If the single space member is formed, it must be formed at the wastefully large size.
Further, in case of a type in which a charge roller is provided in contact with a photoconductor drum, that is, in case of a contact electrification type process cartridge, vibration in conveyance causes reverse rotation of the photoconductor drum, whereby the charge roller is stained, so that bad printing is caused.